1. Field of the Invention
The present invention relates to a wire laying plate assembly and to a molding process for molding an insulating plate for use with such a wire laying plate assembly.
2. Description of the Related Art
A prior art wire laying plate assembly is used to provide branching points for wiring, such as a wiring harness, and typically is accommodated in an electrical connection box. A typical wire laying plate assembly is identified by the numeral 71 in FIG. 6. The prior art wire laying plate assembly 71 has insulating plates 72 placed one over another and busbars 76 between the insulating plates 72. The insulating plates 72 are made of a synthetic resin, and bosses 73 project from the insulating plates 72 for crimped connection to the busbars 76. More particularly, leading ends 74 of the bosses 73 on the insulating plates 72 are accommodated in boss-escaping portions 75 formed in different insulating plates 72. Further, the busbars 76 are formed with insertion holes 77.
The insulating plates 72 and the busbars 76 are assembled by first inserting the bosses 73 through the insertion holes 77 in the busbars 76. The leading ends 74 of the bosses 73 then are crimped. As a result, the busbars 76 are secured to the insulating plates 72. The wire laying plate assembly 71 is formed by alternately placing the insulating plates 72 and the busbars 76.
The wire laying plate assembly 71 is accommodated in a lower casing 78. In this state, locking recesses 80b formed in an upper casing 79 are engaged with locking projections 80a provided on the lower casing 78 to fix the upper casing 79 to the lower casing 78.
However, if the leading end 74 of the boss 73 is not crimped completely, as shown in FIG. 7, a projecting distance of the boss 73 is longer than the depth of the boss-escaping portion 75, thereby creating a problematic clearance between the insulating plate 72 and the busbar 76. Thus, a portion (tab) of the busbar 76 that projects from the upper surface of the insulating plate 72 is likely to be shorter, which causes a connection error between the busbar 76 and an unillustrated connector. Further, the upper casing 79 cannot be fitted to the lower casing 78 using the locking projections 80a and the locking recesses 80b. 
Attempts have been made to solve the above-described problems by deepening the boss-escaping portions 75. Such an attempt to deepen the boss-escaping portion 75 typically would be made when the resin for the insulating plate 72 is injected into a mold 81; However, the resin 82 may not fill the mold 81 completely, as shown in FIG. 8. Thus, a short shot occurs at a portion which is supposed to become the bottom of the boss-escaping portion 75, resulting in a molding error of the insulating plate 72. Accordingly, it has not been possible to ensure a sufficient depth of the boss-escaping portion 75.
Additionally the thickness of the busbars 76 is smaller than the space between the insulating plates 72. Therefore, clearances are formed between adjacent insulating plates 72 regardless of the crimped states of the leading ends 74 of the bosses 73. Such clearances cause the insulating plates 72 and the busbars 76 to shake with respect to each other, thereby creating a noise.
The present invention was developed in view of the above problems, and an object of the invention is to provide a wire laying plate assembly .that can be assembled securely by preventing a molding error of insulating plates. The invention also was developed to provide a molding process for molding an insulating plate for use with such a wire laying plate assembly.
The subject invention is directed to a wire laying plate assembly with a plurality of insulating plates. The insulating plates may be resin-molded products. At least one boss projects from a first of the insulating plates, and at least one boss-escaping portion is formed in a second of the insulating plates at a location to register with the respective boss. The boss-escaping portion is dimensioned for accommodating a leading end of the boss. Additionally, each boss-escaping portion is formed to become gradually deeper toward its center from its outer periphery. The wire laying plate assembly further comprises at least one busbar located between the first and second insulating plates. The busbar is formed with insertion holes at locations that will register with the boss. Thus, the boss of the first insulating plate can be inserted through the respective insertion hole in the busbar and into the respective boss-escaping portion of the second insulating plate to secure the busbar between the insulating plates, thereby assembling the insulating plates and the busbar.
Preferably, the first insulating plate is placed substantially on the second insulating plate with the busbar arranged between the first and second insulating plates.
The bosses preferably are crimped or deformed to secure the busbars to the insulating plates.
According to a further preferred embodiment, a wire laying plate assembly has bosses that project from a first resin-molded insulating plate. The bosses can be crimped, deformed, flattened or inserted for connection. Boss-escaping portions are formed in a second insulating plate for accommodating the leading ends of the bosses of the first insulating plate. The bosses are inserted through insertion holes formed in busbars located between adjacent insulating plates and are crimped to secure the busbars to the insulating plates, thereby assembling the insulating plates and the busbars.
The boss-escaping portions become gradually deeper toward their centers from their outer peripheries. Thus, even if deep boss-escaping portions are formed, a resin is completely filled at the bottom portions of the boss-escaping portions, thereby preventing an occurrence of a short shot during molding. Therefore, a molding error of the insulating plates can be prevented, and the wire laying plate assembly can be assembled securely.
Preferably, a tapered surface is formed at the outer periphery of the bottom surface of each boss-escaping portion. The tapered surface prevents a short shot while ensuring a sufficient depth for the boss-escaping portions. Thus, the leading ends of the bosses are fitted securely in the boss-escaping portions, and the insulating plates are held in close contact with each other. Therefore, the wire laying plate can be assembled more securely.
The insulating plates preferably are formed with recesses for at least partly accommodating the busbars. Each recesses preferably is formed with a terminal piece. The depth of each recess preferably is approximately equal to or slightly less than the thickness of the respective busbar. Accordingly, the busbars and the insulating plates are held in close contact with each other. Thus, the wire laying plate assembly can be assembled securely. Further, noise caused by shaking of the insulating plates and the busbars with respect to each other can be prevented.
The diameter of the leading ends of the bosses preferably is smaller than or substantially equal to the inner diameter of the boss escaping portions.
Most preferably, a thickness of central bottom portions of the boss-escaping portions is about ⅓ the thickness of the insulating plates, and/or a thickness of the peripheral bottom portions of the boss-escaping portion is about ⅓ to ⅔ the thickness of the insulating plates.
The invention also is directed to a process for molding an insulating plate for use with a wire laying plate assembly. The process comprises introducing a melted resin into a mold that has a projection projecting from an inner surface thereof. The resin is introduced from a side portion toward a center portion of the projection along a tapered portion inside the mold. The process then comprises substantially curing the resin inside the mold and opening the mold for withdrawing the mold insulation plate.